Suspension roof support



v Jan- 25, 1954 E. M. THOMAS ETAL 2,667,037

SUSPENSION RooP SUPPORT Filed Aug. g4, 1949 2 Sheets-Sheet 2 Patented Jan. 26, 1954 EdwardM.. Thomas; College Park,

and Anthony J.

Barryfy University-Park,A Md.. ApplicationAug-ust'Zl, 1949, Serial No. 112,152

G-iGlaims. 1

Thisl invention relates to thesupporting of roofs of mines and. other undergrounci workings; and more partieul'arlyA to suspensionsupports or roof` bolts for supporting timbering elements. or cross beams against the' roof-i of such; al mine: or underground` working, thereby eliminating the need of uprights er props beneath the endsoftbe cross timbers or beams.

In the excavationVr of" mines andvarious-types ci' subterranean tunnels, itist'he customary practice. as the mine or tunnelE is extended; to: place' cross timbers underfthe stratied rock'or*earth:forma-l tion which' forms the roof of`the= mine or tunnel to prevent roof fallsv or cave-ins; These cross timbers or roof" supports arey ordinarily held: up against' the roofy of the'mine or tunnel-fb'y vertical posts or props arranged at each side of the entry or tunnell beneath the ends of' the cross timbers; usually spaced quits` close togetherfa. considerable amount of` timberl is employed? for.Y timb'ering; Also since the' timber isusuali'y ofsubstantial-dimensionsit reduces the useful' width oftheentry or tunnel and' requires` added' clearance for'mine cars, locomotives and other mining equipment. The present' invention contemplates. improve.- ments over known types of" roof supportsfor undergroundi mines or: tunnels whereby the'V root.l supported in; a ncveli manner without theuseiof vertical posts or propsfo'rlioliiing-thecross beams c orv otherroof supporting mei'nbersin.p'l'ace. Such type of prop-eliminating roofsupports arefpar'- ti'cularly desirable-for use-'withicontinuous mining apparatus which is becoming prominent. in the continuous mining oi coal or'other minera-ls.

The present invention has for its main;y object to provideimproved' suspension supports which may' bev anchoredfin tbe-L stratied roofofithe mine entry-#oretunnei and provide supportsffor tine-1 cross beams or" other` supporting members. which` are placed against the roof; Another objectf is. to provide animproved tension bolt?.structurefwhera by the cross beams or other#supporting.l members may bermlylield in: place-against the ronf A further object i's to providelimprovezitensionf belt structures which are placed in holesf suitably drilled 0r` otherwise formed" in' the.strafti-1'-`reo`l roof and; firmly 'securedi in position therein whereby the possibility ofA undesired release of. the.' bolt structures is reduced* t'o af minimum; Yet' an other obj ect is to provide improved expansionibot structureswhereby the; supporting bcits: for the cross beams err other" supporting mem-bers may be ljocked in piace and. rmly= seeureif as bye-ce inenting in position; Yet anotherV obg'eet-i is--to f Since the'. customary v rootV` Supports; are n K jects and advantages: of' thea ever, morek fully' appear.

provide improved means for sealngtheilioleitrom thev atmosphere after the expansion` bolt se'- cured in place in the hole'. Theseandi otlier-ob^ invention-will how In the accompanying` draw-ings' there are shown for purposes off' illustration two forms which the invention may assume in practice:

In these drawings:

Fig. 1 is a fragmentary sectional viewJ through a section of the roof stratashowing theiimproved expansion bolt prior to'A securing: tlie` same inexe panded position in a: hole"` d'rlled inA the roof strata.

Fig. 2 is a fragmentary sectional: viewsimilar to Fig. 1, Showing the expansion boirduriagivne cementing operation.

Fig. Bis an enlarged cross sectionalviewtaken substantially 0nnne 3=si Greig. 1.

Fig. 4"' is an enlarged centrali longitudinal' tional View'through the improved expansion 'colti Fig. 5^: is a somewhat diagrammatic cross'4 sectional View througha mine entryz orftunnel? show'- ing'a; cross beam secured imposition bythe'anelior bolts: againstr the rooY..

Fig. 6 is a fragmentary sectional? ViewY similar to Fig. 1f, showing a; modified form of expansion bolt construction.

Eig. 7 is aY View' similary to Eig: di snowing` tl'ie expansionY bolt in expanded position and a cementing orV groutingr means associa-ted; therewith.

Fig'. 8T is a similar view showing' ther anchor boltsecuredf firmly' in*` the rockstrat'a ini a pesi-- tion tosupport the cross beam against'zthercof Fig: 9l is a somewhzeitdiagrammatic cross` seen tional View through a mineentry ontunnelsliowing ai cross beam'. secured in positionl against`= the reef' by.i meansS off the modified anchor bolts:-

As shown in. theidrawirrgs; Ac designates-tirando lwalls or ribs of a mine entry'm:i tunne; Bi i'sa tn:- roof; and Ci roof supports which may be either timbers or structural'` steer cross beamsA herein-s sirably tl`1elatterdue to thergreater' compact ness. They cross. beams; extend substantially across the full? width'. of.' the' entry or tunnel! up against the roof; and.J are supported. in position by the suspension supports s constituting' tlieepresrent invention.

In the illustrative embodimentsbown'zinzligsrl to 5y inclusive; the: suspension: supports or neef boltsv are generally designated andare each@ pn;- sitionerif` in. oblique: hole; D: suitably; di'illerl or otherwise;- formedfin the rockistrata (unearth roliamation: which forms the roofl oftgrehentryfortungnel.` Eachsuspension support' orf root`r belt termS` when the bolt is so .suitable hand gun or pump prises an elongated tubular body or bolt portion 2, desirably of cylindrical form, having a threaded lower end portion 3 which is threadedly engaged by a nut 4. Each cross beam C has appropriately located openings through which the bolts pass, and angle washers 6 surround the bolts between the nuts 4 and the cross beam and lie against the bottom face of the latter in the manner shown. The upper end portion cf the bolt is threaded at 1 and threadedly engages a wedgeshaped sleeve 3 as shown in Fig. 4. Surrounding the upper portion of the bolt and resting at its lower end against a washer 9 seated against a shoulder I0 on the bolt, is a sleeve II which is slotted as at I2 to provide resilient fingers I3. The washer 9 and sleeve I I provide an outwardly offset enlarged head portion on the bolt 2. The bolt may have a polygonal socket I4 or polygonal end portion adapted for engagement by a suitable rotating instrument such as a wrench. Thus when the bolt is suitably rotated the wedgesleeve 8 is forced inwardly within the split sleeve II to expand the fingers I3 thereof into firm contact with the walls of the drill hole to secure the bolt in position. The tubular bolt body has a central bore I6 and lateral openings I'I traversing the bolt a short distance below the shoulderIIJ in the manner shown, and the lower end of this bore is threaded at I8 for connection of a suitable attachment I9 for a pipe or hose '20 (Fig. 2). When the roof bolt is secured in its expanded position in the hole D as shown in Fig. 2 wherein it firmly holds the cross beam C against the roof a quick-hardening cement or other ller may be pumped through the pipe 20, the bore I6 in the bolt and the lateral holes I'I into the space surrounding the bolt and into the hole which receives the expansion device so that the anchor bolt is firmly held in place when the cement or filler hardens or sets'. air from the hole. The tubular body of the expansion bolt may be suitably corrugated along its exterior periphery or may be provided with suitable projections 2I spaced along its length to aid the enlarged head portion in securing the bolt in position in the rock strata. By tightening the nuts 4 of the bolts against the angle washers 6 the cross beam may be rigidly held in place against the roof in the manner shown in Fig. 5. Now referring to the modified construction shown in Figs. 6 to 9 inclusive it will be noted that the anchor bolt comprises a cylindrical body portion having a threaded lower end portion 26 and the upper end portion of the bolt is formed with an outwardly offset enlarged head portion 21. This head portion is longitudinally split at 28 to provide resilient fingers 29 which have tooth-like serrations 30 on their outer surfaces. The inner walls 3I -of the resilient fingers 29 are relatively inclined and a vwedge`32 is placed in the tapered space between the fingers as shown in Fig. 6. When the bolt is driven inwardly the wedge 32 contacts the bottom of the drill-hole so that as -driving in of the bolt is continued the fingers 29 are expanded to bring the teeth thereof into rm contact with the walls of the hole. In Fig. 7 the anchor bolt is shown in expanded position and arranged a yieldable hood 35 encloses the lower end of the bolt and tightly contacts the roof to provide a substantial seal at the mouth of the drill-hole. An air vent tube 36 extends through this seal into the drill-hole along the side of the bolt in the manner shown.

31 which is filled with .quick-hardening cement or other filler has its The cement also seals out nozzle 38 extended through a hole 39 in the hood so that when the pump is operated the cement or grouting is discharged into the space between the bolt body and the walls of the hole. During this pumping operation any air in the hole is discharged through the vent tube 36 and as the space becomes lled with cement the vent tube may be withdrawn from the hole, When the cement becomes hardened the anchor bolt is firmly held in place in the rock strata and the hole is sealed to atmosphere. The cross beam C is then placed against the roof, the angle washer inserted in position and a nut 40 threaded on the lower end of the bolt may then be tightened to secure the cross beam rmly against the roof. In Fig. 9 the cross beam is shown secured in position against the roof of the mine entry or tunnel by means of the appropriately located anchor bolts.

In both embodiments of the invention evidently various other types of conventional expansible bolt heads may be employed in lieu of those disclosed. Moreover, in both employments, the mode of use of the suspension supports is essentially the same. The holes are first suitably formed in the desired location in the roof strata., the suspension bolts are then inserted in the holes and suitably expanded into contact with the holes walls, and finally quick-setting cement or filler is pumped into the spaces around the bolts to secure the latter firmly in position in the roof strata and to seal the hole. When the bolts are properly fixed in place the cross beams are placed in position against the roof with the lower ends of the bolts extending through the openings in the beam,

' and the nuts are then threaded onto the bolts and tightened to secure the cross beams against the roof.

As a result of this invention an improved roof supporting means is provided for mines or other underground workings whereby the usual upright timbers or props are eliminated thereby providing the mine entry or tunnel with greater useful width and increasing the roof clearance. One of the advantages of the improved roof support is that the suspension supports or roof bolts used for the purposes of the invention, are firmly supported in holes drilled in the roof strata and are thereby prevented from bending or buckling as generally occurs in the case of timber-props. Props, moreover, are liable to slip on off-center loading, just when stability is most required. Moreover, if, after the cross beam or other supporting member has been drawn into contact with the roof by the bolts, the roof sags slightly, the roof support will still be firmly held in position. Another advantage of the improved roof support is that the cross beams or other supporting mem* bers may be secured in place against the roof immediately after the coal or other 'material has been broken down and before its removal, before the subsidence of the roof has started. By cementing the tension bolts in the roof strata, danger of the bolts pulling loose, is substantially avoided. The cement not only firmly secures the bolts in place but also seals the drill hole to the atmosphere, thus retarding disintegration of the roof rocks, and, Where water is encountered in drilling, prevents corrosion of the steel supporting bolts. Other uses and advantages of the in vention will be clearly apparent to those skilled in the art. f

While-there arein this application specincalls7 described-two forms which the inventionmay as sume in practice, it will be understood that these forms of the same are shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What We claim as new and desire to secure by Letters Patent is:

1. A supporting structure for the roof supports of a mine or the like, comprising a plurality of anchor bolts secured in position in holes formed in the roof strata, each bolt comprising an elongated hollow body, an enlarged expansible head at the upper end of the body outwardly offset therefrom, mechanical means for effecting expansion of the bolt head to secure the bolt in firm contact `with the holding-walls, said bolt having means for conducting a quick-setting cement into the spaces around the bolt and expanded bolt head within the hole to effect firm securing of the bolt in supporting position in the roof strata.

2. A supporting structure for the roof supports of a mine or the like, comprising a plurality of anchor bolts secured in position in holes formed in the roof strata, each bolt comprising an elongated hollew body, an enlarged expansible head at the upper end of the body outwardly offset therefrom, mechanical means for effecting expansion of the bolt head to secure the bolt in firm contact with the holding-walls, said bolt having means for conducting a quick-setting cement into the spaces around the bolt and expanded bolt head within the hole to effect firm securing of the bolt in supporting position in the roof strata, said means for conducting cement to the hole around the bolt including a passage in the bolt communicating with the space around the bolt just below the expanded bolt head.

3. A supporting structure for the roof supports of a mine or the like, comprising a plurality of anchor bolts secured in position in holes formed in the roof strata, each bolt comprising an elongated hollow body, spaced projection means on said body, enlarged expansible head at the upper end of the body outwardly oifset therefrom, mechanical means for effecting expansion of the bolt head to secure the bolt in firm contact with the hole-walls, said bolt having means for conducting a quick-setting cement into the spaces the hole to effect firm securing of the bolt in supporting position in the roof strata, said means for conducting cement to the hole around the bolt including a passage in the bolt communicating with the space around the bolt just below the expanded bolt head and a supply attachment associated with the lower end of the bolt.

4. A supporting structure for the roof supports of a mine or the like, comprising a plurality of anchor bolts secured in position in holes formed in the roof strata, each bolt comprising an elongated body, an expansible head at the upper end of the body, mechanical means for effecting expansion of the bolt head to secure the bolt in iirm contact with the hole walls, said bolt having means for conducting a quick-setting cement into the spaces around the bolt and expanded bolt head lwithin the hole to effect firm securing of the bolt in supporting position in the roof strata including a supply attachment mounted adjacent the lower end of the bolt comprising a flexible sealing hood enclosing the lower end of the bolt and tightly engaging the roof at points surrounding the mouth of the hole.

5. A supporting structure for the roof supports of a mine or the like, comprising a plurality of anchor bolts secured in position in holes formed in the roof strata, each bolt comprising an elongated body, an expansible head at the upper end of the body, mechanical means for effecting expansion of the bolt head to secure the bolt in firm contact with the hole-walls, said bolt having means for conducting a quick-setting cement into the spaces around the bolt and expanded bolt head within the hole to effect rm securing of the bolt in supporting position in the roof strata including a supply attachment mounted adjacent the lower end of the bolt comprising a flexible sealing hood enclosing the lower end of the bolt and tightly engaging the roof at points surrounding the mouth of the hole, and an air vent tube extending from the exterior of said hood into the hole.

6. A supporting structure for the cross beams which support the roof of a mine or the like comprising a plurality of anchor bolts secured in position in cbliquely disposed holes formed in the roof strata, the cross beams having holes through which the lower ends of the bolts extend and said bolts having nuts threaded on their lower portions for firmly securing the cross beams against the roof, each of said bolts comprising an elongated body insertible in a hole and having an enlarged expansible upper head outwardly offset from said body, means for effecting expansion of said head to cause the bolt to grip the holewalls, said bolt having means for conducting a quick-setting cement intothe spaces around the bolt body and said expanded head for firmly securing the bolt in position in the hole, said conducting means embodying means for preventing discharge of cement through the mouth of the hole during filling of the hole-spaces.

EDWARD M. THOMAS. ANTHONY J. BARRY.

References Cited in the file of this patent OTHER REFERENCES Engineering and Mining Journal, May 1943, pages -72. 

